This invention relates to closures for containers and more particularly to closures for containers used in storing parenteral solutions and the like.
The majority of containers currently in use for storing and dispensing parenteral or irrigation solutions or the like are semi-rigid or collapsible plastic containers. Parenteral solution containers typically have a spike entry port and a medicinal entry or additive port with piercable diaphragms. To preserve the surface sterility of these ports, they are protected by outer closures which are generally hermetically sealed over or around these ports and are removable prior to the ports being entered by a spike of an administration set or a needle or spike of an additive solution container. Typical of such closures are those shown in U.S. Pat. Nos. 3,394,831, 3,978,859, 4,111,324, 4,187,893, 4,199,071, 4,207,988 and 4,228,835. U.S. Pat. Nos. 3,281,007, 3,407,957 and 3,981,412 are representative of those which show removable plastic closures on containers used in the soft drink industry.
The closures referred to in these patents all suffer certain deficiencies. A portion of the closure in each case is removed by rupturing of a thinned section or scoreline. However, the initiation of rupture is often difficult, particularly with the types such as those shown in patents 3,981,412 and 3,978,859. In addition, most of the closures in the above-cited patents are generally more expensive and difficult to mold in commonly used injection molding operations than a more simplified design as shown in patent 3,981,412 for example.